The floods, triggered by torrential monsoon downpours, have engulfed Pakistan's Indus river basin, killing more than 1,600 people, forcing two million from their homes and disrupting the lives of about 14 million people, or eight percent of the population.

Although waters have receded in some areas, fresh rains could bring new destruction, and a health crisis would tax aid agencies already facing huge logistical challenges.

The United Nations is increasingly concerned about water-borne diseases. At least 96 health facilities have been damaged across the country, and there are 36,000 suspected cases of potentially fatal acute watery diarrhea reported so far.

"This is a growing concern. Therefore we are responding with all kinds of preventative as well as curative medication... for outbreaks," said Maurizio Giuliano, the U.N. humanitarian operation spokesman told Reuters.

The floods have roared down from the northwest to the Punjab agricultural heartland to the southern Sindh province, where new floods are possible.

The deluge, which began two weeks ago, has caused extensive damage to the country's main crops, agriculture officials said, after the United Nations appealed for $459 million in emergency aid and warned of a wave of deaths if help didn't arrive.

Increasing desperation could lead to social unrest and pile more pressure on the government, which has already been heavily criticized for its perceived lackluster response to the floods, unlike the powerful military which swung into action.

"There is a huge need for food. All over the country crowds are in need of food," said Giuliano.

ECONOMY HAMMERED

Entire villages have been swallowed up. Fertile lands have been destroyed, stripping farmers of their livelihood. Bridges have collapses. People desperate to keep their livestock walk neck-deep in water, pulling the animals along.

The International Monetary Fund has warned of major economic harm and the Finance Ministry said the country would miss this year's 4.5 percent gross domestic product growth target though it was not clear by how much.

Wheat, cotton and sugar crops have all suffered damage. Agriculture is a mainstay of the economy and the United Nations has estimated rehabilitation will cost billions of dollars.

"There may be severe shortages too and riots could well break out," said independent economist Meekal Ahmed. "The power shortage which has crippled industry could get worse. Exports would be hit as well."

Cholera would create another major crisis, but determining if there has been an outbreak is difficult.

"Acute watery diarrhea is on the rise but we have limited access to some of the areas. The access is hampering our efforts to reach and attend to these cases," said Dr. Irshad Sheikh, regional advisor for emergency preparation and humanitarian access for the World Health Organization.

"You don't have access to labs in those areas so cannot confirm if it is actually cholera."

President Asif Ali Zardari has just started what appears to be damage control by visiting flood victims after drawing heavy criticism for leaving for meetings with European leaders the disaster unfolded and not cutting his trip short.

Zardari said he had worked to secure international aid for the flood victims during his trip. Despite the government's increasing unpopularity after its handling of the floods, analysts rule out a military grab for power.

Giuliano said the floods have affected about one third of Pakistan "at one point or another."